03/31/2015. Remarks by Johan Visschedijk: "In September 1940, Percival Hopkins "Spence" Spencer formed his own company, and his resulting design was the Spencer S-12 Air Car Amphibian. Construction of the S-12 began on March 1, 1941 and the small two-seat S-12, registered NX29098, made its first flight on August 8, 1941, from sea on Belmore, Great South Bay, Long Island. The S-12 was a fabric covered amphibian with a unique boxlike forward cabin, a high wing with a two bladed propeller in pusher configuration and a long, slender tail boom.

In December 1941 Spencer put the S-12 into storage and joined the war effort as a test pilot for the Republic Aircraft Corporation. In April 1943 Spencer left Republic Aircraft to join the Mills Novelty Company of Chicago, Illinois who wanted to use his Air Car to promote their company. Spencer used the company's wood forming equipment to build a new egg-shaped cabin for the S-12 and began demonstrating the aircraft to his former employers, Republic Aircraft. Seeing the potential of the type as the perfect sports plane for pilots returning from the war, Republic purchased the rights to the S-12 in December 1943 and immediately began development of an all-metal version designated RC-1 Thunderbolt Amphibian.

By the 1970s, Spencer had developed the S-12 into a homebuilt aircraft."